These gases are called greenhouse gases. The three most important greenhouse gases are carbon dioxide, methane
and nitrous oxide and these have increased dramatically in recent years due to human activity.
The Earth is known as a ‘closed system’ which means that it produces everything it needs to ensure the
survival and growth of its residents. In nature there are chemical cycles such as the carbon cycle to control and
balance these gases that surround the Earth. The carbon cycle is a complex series of processes through which all of the carbon atoms in existence rotate. This means that the carbon atoms in your body today have been used in many other molecules since time began e.g. as the carbon found in carbon dioxide in the air. Microbes play an important role as either generators or users of these gases in the environment as they are able to recycle and transform the essential elements such as carbon and nitrogen that make up cells.